I took a look at one of your earlier Audiogon threads, and it's obvious that you have been doing some "heavy lifting" in your audio hobby.
I congratulate you for your passion, energy, and curiosity. While I have always been fascinated with tonearm design, building turntables has kept me too busy to delve into this area. You can likely teach me a thing or two about arms.
In things audio, I am of the opinion that one can select various different architectures and solve the technical problem quite nicely.
In tonearms for example, I have seen excellent fixed bearings, unipivots, and of course string tension devices like the Schröder and Well Tempered arms. I need to note that it has been quite a few years since I've listened to a WT arm however.
More important than the choice of basic architecture, is the maturity of the design and the precision of its execution.
One of the reasons Frank Schröder was so free in his description of his basic tonearm design architecture (in one of the DIY forums) is that there are still quite a few nasty details to work out. Frank wouldn't want to take away all of your joy of discovery, would he?
Additionally, precision manufacturing is critical to the fabrication of a Schröder tonearm, even if it is not a fixed bearing design. The tonearm's simplicity belies its sophistication.
The issues inherent in designing a tonearm which does not dissipate energy through the bearing (into the turntable base) are substantially different than those where there is a mechanical pathway (fixed bearings and unipivots).
My guess is that part of what you are hearing relates to these concepts (energy reflecting back to the cartridge) as well as to perhaps the choice of string material (damping / stiffness), magnet strength (damping again), and arm wand material (damping, energy dissipation).
Please don't take these comments as a sales pitch for Schröders. My goodness ... it is difficult to keep the waiting list short enough.
My intent is rather to encourage you to go back to your experiments and continue discovering. I admire your curiosity and perseverance.
Thom @ Galibier